[#5] Pass gfx structs by const ref (gfx::Vector2dF)

cc/base/math_util.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/base/math_util.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 
@@ skipping 474 matching lines @@
     return gfx::Vector2dF(fallback_value, fallback_value);
   float x_scale = ScaleOnAxis(transform.matrix().getDouble(0, 0),
                               transform.matrix().getDouble(1, 0),
                               transform.matrix().getDouble(2, 0));
   float y_scale = ScaleOnAxis(transform.matrix().getDouble(0, 1),
                               transform.matrix().getDouble(1, 1),
                               transform.matrix().getDouble(2, 1));
   return gfx::Vector2dF(x_scale, y_scale);
 }
 
-float MathUtil::SmallestAngleBetweenVectors(gfx::Vector2dF v1,
-                                            gfx::Vector2dF v2) {
+float MathUtil::SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
+                                            const gfx::Vector2dF& v2) {
   double dot_product = gfx::DotProduct(v1, v2) / v1.Length() / v2.Length();
   // Clamp to compensate for rounding errors.
   dot_product = std::max(-1.0, std::min(1.0, dot_product));
   return static_cast<float>(Rad2Deg(std::acos(dot_product)));
 }
 
-gfx::Vector2dF MathUtil::ProjectVector(gfx::Vector2dF source,
-                                       gfx::Vector2dF destination) {
+gfx::Vector2dF MathUtil::ProjectVector(const gfx::Vector2dF& source,
+                                       const gfx::Vector2dF& destination) {
   float projected_length =
       gfx::DotProduct(source, destination) / destination.LengthSquared();
   return gfx::Vector2dF(projected_length * destination.x(),
                         projected_length * destination.y());
 }
 
 scoped_ptr<base::Value> MathUtil::AsValue(gfx::Size s) {
   scoped_ptr<base::DictionaryValue> res(new base::DictionaryValue());
   res->SetDouble("width", s.width());
   res->SetDouble("height", s.height());
@@ skipping 91 matching lines @@
   return scoped_ptr<base::Value>(base::Value::CreateDoubleValue(
       std::min(value, std::numeric_limits<double>::max())));
 }
 
 scoped_ptr<base::Value> MathUtil::AsValueSafely(float value) {
   return scoped_ptr<base::Value>(base::Value::CreateDoubleValue(
       std::min(value, std::numeric_limits<float>::max())));
 }
 
 }  // namespace cc